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STDU Viewer - an advanced PDF, DjVu and multi-page TIFF viewer  If you occupation involves a lot of reading (especially of technical texts), you may have noticed that all the documents usually come in one of the following formats: PDF, DjVu and multipage TIFF. Unfortunately, these are three independent file formats that require separate viewers, which creates a certain problem. If you need an all-in-one viewer that will read all these formats with equal efficiency, make sure not to miss STDU Viewer! STDU